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A week and a half ago, my husband took our problem-free 2002 Jeep Liberty in for a routine oil change. It's got 115k on it, but has had regular maintenance and was running fine. The oil change shop says our radiator cap is bad and we need to have it replaced, so he oks it.

Monday, the engine overheats on the 3 mile drive home from the train station, red lining and stalling in our driveway (no steam). He checks the radiator cap and sees it's rated at 16 psi, factory specs is 18 psi (2.4 litre vs. 3.7). It sits on Tuesday and the shop swaps out a new radiator cap, 18 psi. On a drive this afternoon, the temp stays stable, but it starts stalling at a stop sign. After a rest, it starts up again. Stalls again pulling into a parking spot. Stalls again turning a corner. And again.

When it stalls, we still have lights and radio, but no power breaks or power steering. No weird noise, just quiet. Other that stalling, it starts right up. Fan is running. Our thermostat was replaced last year, as was the alternator. Could a wrong radiator cap have caused this or is it just a coincidence?

Was the coolant level low when you overheated? Using a cap rated for a lower pressure won't directly cause the vehicle to overheat , it will only allow the radiator to boil over at a lower temperature. So if it boiled over a little each day it might have lost enough coolant in a week to overheat.

If the coolant level wasn't low then the whole thing is probably unrelated to the cap. So we'd either be looking at something else that happened in the shop or a complete coincidence.

I don't think the stalling is related either way unless, as Frank suggested, the overheating may have caused something else to fail.

A week and a half ago, my husband took our problem-free 2002 Jeep Liberty in for a routine oil change. It's got 115k on it, but has had regular maintenance and was running fine. The oil change shop says our radiator cap is bad and we need to have it replaced, so he oks it.

Monday, the engine overheats on the 3 mile drive home from the train station, red lining and stalling in our driveway (no steam). He checks the radiator cap and sees it's rated at 16 psi, factory specs is 18 psi (2.4 litre vs. 3.7). It sits on Tuesday and the shop swaps out a new radiator cap, 18 psi. On a drive this afternoon, the temp stays stable, but it starts stalling at a stop sign. After a rest, it starts up again. Stalls again pulling into a parking spot. Stalls again turning a corner. And again.

When it stalls, we still have lights and radio, but no power breaks or power steering. No weird noise, just quiet. Other that stalling, it starts right up. Fan is running. Our thermostat was replaced last year, as was the alternator. Could a wrong radiator cap have caused this or is it just a coincidence?

ETA: No check engine light or other warning light comes on

First of all, there's a 99.9% chance that your radiator cap was perfectly fine. That is not a "wear part." But I'm sure they charged you a lot for that $5 part.

Second, unless they jacked with something else, simply replacing a radiator cap should not have caused that much drainage of the anti-freeze.

Basically, I would be royally PO'd at this "mechanic shop" and would raise holy hell with them. A perfectly fine-running car, that leaves their shop screwed up, is almost certainly not a coincidence.

A week and a half ago, my husband took our problem-free 2002 Jeep Liberty in for a routine oil change. It's got 115k on it, but has had regular maintenance and was running fine. The oil change shop says our radiator cap is bad and we need to have it replaced, so he oks it.

Monday, the engine overheats on the 3 mile drive home from the train station, red lining and stalling in our driveway (no steam). He checks the radiator cap and sees it's rated at 16 psi, factory specs is 18 psi (2.4 litre vs. 3.7). It sits on Tuesday and the shop swaps out a new radiator cap, 18 psi. On a drive this afternoon, the temp stays stable, but it starts stalling at a stop sign. After a rest, it starts up again. Stalls again pulling into a parking spot. Stalls again turning a corner. And again.

When it stalls, we still have lights and radio, but no power breaks or power steering. No weird noise, just quiet. Other that stalling, it starts right up. Fan is running. Our thermostat was replaced last year, as was the alternator. Could a wrong radiator cap have caused this or is it just a coincidence?

ETA: No check engine light or other warning light comes on

The red lining most likely caused engine damage. He should have shut the car off as soon as he saw that.

If the radiator fluid was significantly low, I would look very suspiciously at the cap myself... If the Lib's 3.7 is set to operate as "normal" with up to 18 lbs of pressure in the radiator, and they put a cap on that will start releasing pressure at 16 lbs, it may have spent a week slowly venting out radiator fluid. Once there isn't enough left, the engine overheats, which can cause all kinds of damage.

Here's the problem SS, regardless of the cause of the stalling, yer looking to replace the car or engine pretty soon. Probably as soon as the first cold snap comes to your area. Aluminum engines do not tolerate excessive heat. I can assure you something is now broke, be it a metal part or a gasket. When the thermal differences of ambient air and combustion temps takes place this winter, you'll be looking for a mechanic or a car dealership to unload that Liberty. If it's in the budget, unload it NOW.

Unless the fools at the shop didn't bother to refill the radiator when they found a defective cap, a cap of 2lbs lighter will not cause the issues you have. While there may be no engine light, you need to have it checked for codes. Some of the auto parts houses have code readers and it's a free service. There's obviously something wrong under the hood and it may be as simple as a loose wire, bad ignition, etc. But that's not going to fix the unforgiving high heat damage that has already happened. The 3.7 has never been a stellar engine or a long life engine. You've just about got all your going to get from it. Hope you're in a position to buy something else.

Quite possible that the incorrect radiator cap was not only the wrong pressure, but the wrong length between the top of the cap and the disc that actually establishes the pressure on the radiator (I am assuming an old school type radiator cap on this Jeep - not the Euro style all-plastic cap...if so the pressure rating made no difference, since it didn't hold any pressure at all. I wouldn't think this would cause the Jeep to overheat, but possible it did.

As I have posted in hundreds of threads here, "stupid lube" quicky oil change outfits are nothing but trouble, stay away.

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